Many portable electronic devices include rechargeable batteries. However, depending on the power consumption of the electronic device, the battery may need to be periodically recharged so that the device may continue to operate uninterrupted. For example, laptop computers often include a battery that powers the device when a traditional power source is not available, but may often only operate for a limited time before the battery must be recharged. Thus, it is useful if a portable electronic device provides some indication to the user of the battery status so that the user may recharge the battery before loss of power. This is especially useful in situations where data may be lost due to a power failure, such as a laptop computer or other portable computing device.
An additional concern is that, although batteries may be refreshed by charging, virtually all batteries suffer degradation over time such that the battery can no longer provide the necessary power to the device even when charged. For example, a typical nickel-metal hydride (NiMH) battery can generally be recharged about 1,000 times before the battery has degraded to a point that it can no longer provide the necessary power to the device. Thus, batteries for electronic devices are typically replaced with new batteries once the performance of the battery degrades. However, in some situations, acquiring a replacement battery for the electronic device may take several days or weeks as the new battery must be obtained from a manufacturer of the device. In situations where data may be lost or usage of the device may be interrupted due to the degraded battery, a user may wish that the electronic device provide an indication to the user that the battery is nearing the end of the battery's life. Ideally, this indication is provided to the user with enough time to allow the user to locate and purchase a replacement battery before any negative effects are realized, such as loss of information or ability to use the device in a portable manner.